Download LECTURE 6 (Joints and Fractures)

JOINTS AND FRACTURES
TERMINOLOGY
Dislocation: when a joint is not aligned properly
Luxation: A dislocation in which the articulating surfaces of a joint are forced entirely
out of position
Subluxation: Damage to a joint so that it is slightly out of its normal position
• Ankylosis: stiffness in a joint, due to rigidity from injury or disease. A surgeon
repairing a damaged joint must be certain to maintain the shape of the articulating
surfaces, because incorrectly apposed articulating surfaces might develop
abnormal ankyloses. Most joints have surfaces that match. If an injury occurs and
the joint surfaces no longer match, bone spurs may form. The joint cannot alter its
shape to adapt.
CLASSIFICATION OF FRACTURES
• SIMPLE (CLOSED)
• Skin is not broken
• Requires cast
• COMPOUND (OPEN)
• Bone has broken through the skin
• Increased chance of infections, which can be life-threatening.
• Requires surgery, hospitalization and IV antibiotics
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INCOMPLETE
• Only one side of the bone is broken
• Hairline (stress) fracture
• Greenstick fracture
COMPLETE
• Both sides of bone is broken
DISPLACED
• Produces new and abnormal bone arrangements
Once you have described if the fracture is open or closed, and complete or
incomplete, then you describe the fracture shape:
• Stress (hairline) fracture
• Greenstick fracture
• Epiphyseal fracture
• Transverse fracture
• Oblique fracture
• Spiral fracture
• Comminuted fracture
• Avulsion fracture
• Impacted fracture
• Compression fracture
• Depression fracture
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STRESS: least serious, get tiny, almost invisible breaks. Usually from overexertion.
Muscle builds up faster than bone. Six weeks into military basic training camp, see lots
of stress fractures from too much new running. Can’t see it on x-ray for three weeks.
Diagnose it by placing a tuning fork on the bone, but not at the area of tenderness…the
vibration travels down the shaft of the bone until it reaches the fracture site. This will be
very painful if it is a stress fracture.
GREENSTICK: most common in children; like breaking a green twig, it’s not
completely broken. Bones in children are not fully mineralized.
EPIPHYSEAL FRACTURE
• The growth plate in the bone of a child is called the epiphyseal growth plate. That
area is weaker than bone, so the whole thing can be broken through during an
injury.
• It is very serious because the bone may grow crooked thereafter. May need
repeated surgeries to straighten the bone as it grows.
TRANSVERSE FRACTURE
• Bone breaks completely through, right to left, in the transverse plane
OBLIQUE FRACTURE
• Bone breaks completely through, from upper to lower, in an oblique plane
SPIRAL FRACTURE
Bone was twisted, such as in skiing or rollerblading.
COMMINUTED
The most serious; bone shatters into three or more pieces. Bone graft might be
needed.
AVULSION FRACTURE
A piece of brone is broken off by the sudden, strong contraction of muscle.
Common sports injury
Often seen with “groin muscle injury”
IMPACTED FRACTURE:
Pressure was exerted on both ends of the SAME bone.
The bone is crushed
Often seen in femur after falling from a height.
COMPRESSION FRACTURE
TWO bones are forced together, and bone is crushed.
Example would be two vertebrae being crushed together from a fall from a
height .People with osteoporosis (loss of bone minerals) often get this type of fracture
spontaneously.
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DEPRESSION FRACTURE
Bone is pressed inward
Often seen in skull fracture from blunt object
PATHOLOGICAL FRACTURE: When the bone (especially the hip bone of someone
with osteoporosis) breaks first, then the patient falls.
Colles’ Fracture
This is a fracture of the distal radius in the forearm with dorsal (posterior) displacement
of the wrist and hand. The fracture is sometimes referred to as a "dinner fork" or
"bayonet" deformity due to the shape of the resultant forearm. Often occurs when a
runner falls on their outstretched hands.
Pisiform Fracture
• Most commonly the pisiform is injured in a fall on the outstretched hand with the
wrist in extension or if the heel of the hand is used like a hammer.
• The bone may need to be removed surgically.
• Being an anchor for several ligaments and muscles, when one fractures the
pisiform, there is a 50% chance of additional fractures in the distal radius or
another carpal bone.
Scaphoid Fracture
• Scaphoid fractures are among the most common injuries.
• They frequently occur following a fall onto an outstretched hand.
• X-rays taken soon after the injury may not reveal a fracture, but diagnosis needs
to be made quickly to prevent death of this bone.
• Scaphoid fractures account for 60-70% of all carpal fractures.
Anatomical Snuffbox
• The anatomical snuffbox is a triangular deepening on the radial, dorsal aspect of
the hand—at the level of the carpal bones, specifically, the scaphoid and
trapezium bones forming the floor.
• The name originates from the use of this surface for placing and then sniffing
powdered tobacco, or “snuff.”
• In the event of a fall onto an outstretched hand, this is the area through which the
brunt of the force will focus.
• This results in the scaphoid bone being the most often fractured of the wrist.
• The scaphoid is a small, oddly shaped bone whose purpose is to facilitate mobility
rather than confer stability to the wrist joint, so it is often the weak link.
• Interestingly, scaphoid fracture is one of the most frequent causes of medico-legal
issues.
• An interesting anatomical anomaly in the vascular supply to the scaphoid is that
blood enters the scaphoid distally.
• In the event of a fracture, the proximal segment of the scaphoid will be devoid of
a vascular supply, and avascular necrosis (death of tissue from lack of blood
supply) will occur if action is not taken.
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When a bone dies from lack of blood supply the condition is called
osteochondritis dessicans.
Due to the small size of the scaphoid and its shape, it is difficult to determine,
early on, whether or not the scaphoid is indeed fractured with an x-ray. Pain in the
anatomical snuffbox is a presumptive diagnosis of a fracture. The patient would
then be sent to get an MRI.
Joints And Their Classification
 A joint, or articulation, is any point at which two bones meet, regardless of
whether they are movable at that point
 The science of joint structure, function, and dysfunction is called arthrology
 The study of musculoskeletal movement is kinesiology
 Kinesiology is the scientific study of human movement. Kinesiology addresses
physiological, mechanical, and psychological mechanisms. Applications of
kinesiology to human health include: biomechanics and orthopedics, strength &
conditioning, sport psychology, rehabilitation, such as physical and occupational
therapy, as well as sport and exercise.
 Individuals who have earned degrees in kinesiology can work in research, the
fitness industry, clinical settings, and in industrial environments.
 Kinesiology is a branch of biomechanics, which deals with a broad range of
motions and mechanical processes in the body.
About Joints
Tendons bind a muscle to bone
Ligaments bind bone to bone
Both are dense regular connective tissue
About Muscles (acting at a joint)
 origin
 insertion
 action
Characterizing Joints
What type of movement does the joint allow?
 No movement, limited movement, free movement
What tissue joins the bones?
 Fibrous Joints
 Fibrous connective tissue (suture, ligament, tooth)
 Cartilaginous Joints
 Fibrocartilage (pubic symphysis)
 Hyaline cartilage, no capsule (epiphyseal plate, costal cart)
 Synovial (Hyaline cartilage with a capsule)
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Classification of Joints by Types of Movement
Synarthrotic
 immoveable, allows no movement
Amphiarthrotic
 allows only limited movement
Diarthrotic
 freely moveable
Classification of joints by the type of tissue between bones
Suture (dense CT between bony plates)
Syndesmosis (ligament)
Gomphosis (tooth socket)
Symphysis (fibrocartilage)
Synchondrosis (hyaline cartilage)
Synovial (fluid filled joint)
Classification of joints by type of tissue between bones:
Ask yourself…is the tissue Fibrous or Cartilaginous?
FIBROUS JOINTS (dense fibrous connective tissue…don’t confuse this type of joint
with fibrocartilage!)
 A fibrous joint is two bones joined by fibrous connective tissue.
 No joint cavity
 Some fibrous joints are immoveable (sutures and gomphoses) and some are
slightly moveable (syndesmoses, which means ligaments)
TYPES OF FIBROUS JOINTS
Sutures (immoveable = synarthrotic)
Gomphoses (immoveable = synarthrotic)
Syndesmoses (slightly moveable = amphiarthrotic)
Suture
• In sutures and gomphoses, the fibers are very short and allow for little or no
movement
Gomphosis
 Tooth sits like a peg in a socket.
 The peridontal ligament holds it in place.
Syndesmosis
• In syndesmoses, the fibers are longer and the attached bones are more movable:
These are ligaments
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CARTILAGINOUS JOINTS
 A cartilaginous joint is two bones joined by cartilage. The cartilage is either
fibrocartilage (a symphysis joint) or hyaline cartilage (a synchondrosis).
 Fibrocartilage joints (symphyses) are amphiarthrotic (slightly moveable).
 Examples are intervertebral discs and the pubic symphysis
 Hyaline cartilage joints (synchondroses) are synarthrotic (immovable).
 Examples are epiphyseal plates and costal cartilages
Symphysis
In a symphysis, two bones are joined by fibrocartilage (A symphysis is amphiarthrotic:
slightly moveable). Example is intervertebral discs.
Synchondrosis
A synchondrosis is a joint in which the bones are bound by hyaline cartilage (A
synchondrosis is synarthrotic: not moveable)
INTERVERTEBRAL DISCS
Function is for suction, shock absorption, and a little movement. Made up of outer ring
of fibrocartilage called the ANNULUS FIBROSIS, and the middle section is elastic
cartilage called the NUCLEUS PULPOSIS, which provides the cushion. Why do we
need an annular fibrosis ring? The nucleus pulposis is like a rubber ball. When you
compress it, it can be flattened. The ring keeps it from compressing all the way.
HERNIATED intervertebral disc happens when stress is put on it the wrong way. When
you bend over, the disc compresses anteriorly. If there’s a weakness there, the annulus
fibrosis tears, and the nucleus pulposis herniates (pokes out). It can press on the spinal
nerves and cause a lot of pain or some paralysis. Improper lifting and pushing with the
back can cause this. One treatment is to put a metal rod in to maintain the distance
between the discs.
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SYNOVIAL JOINTS
 The most familiar type of joint and the most common. It allows a wide range of
motion so it is functionally classified as a diarthrotic joint (a diarthrosis)
 Examples include the elbow, knee, knuckles, the joints between the wrist and
ankle bones
 Synovial joints are the most structurally complex type of joint, (having a joint
cavity) and are the most likely to develop uncomfortable and crippling
dysfunctions.
Synovial Joint characteristics
• Enclosed chamber, flexible fibrous capsule
• A cavity filled with fluid, synovial fluid
• An inner membrane that produces lubricating fluid, synovial membrane
• Articular cartilages covering ends of bones
• Reinforcing ligaments to stabilize
• Innervated and vascular
In synovial joints, the facing surfaces of the two bones are covered with articular
cartilage, a layer of hyaline cartilage about 2 mm thick.
These surfaces are separated by a narrow space, the joint (articular) cavity, containing a
slippery lubricant called synovial fluid. This fluid is rich in albumin and hyaluronic acid,
which give it a viscous, slippery texture. It nourishes the articular cartilages, removes
their wastes, and makes movements at synovial joints almost friction-free. The
SYNOVIAL MEMBRANE lines the inside of the capsule and is what makes the
SYNOVIAL FLUID.
SYNOVIAL FLUID
1. Lubricates the joint, allows smooth movement. Its viscosity (thickness) changes
with pressure, so bones will never touch, even when you jump up and down.
2. Nourishes articular cartilage (which is Avascular). Every movement puts
pressure on joint, forcing fluid into cartilage. Therefore, you need pressure on
joints to feed the cartilage.
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Capsule
A connective tissue membrane (articular capsule) encloses the cavity and retains the
fluid. It has an outer fibrous capsule, which acts like a sleeve; it is continuous with the
periosteum of the adjoining bones, and an inner, cellular synovial membrane.
In several synovial joints, fibrocartilage grows inward from the joint capsule and forms a
pad between the articulating bones. When the pad crosses the entire joint capsule it is
called an articular disc, or a MENISCUS. Some joints (such as the knee) use these
MENISCI to act as a guide for movement of the bones to prevent unwanted movement
such as lateral movement in the knee (Common injury).
The joint capsule alone is not strong enough, so there are reinforcing LIGAMENTS,
which provide most of the strength of holding the bones to bones. They are dense regular
connective tissue.
In the knee joint, the collateral ligaments are the main ligaments that keep the knee from
moving medially to laterally.
Ligaments take a long time to heal if torn because they do not have blood vessels of their
own, like bones do. They already have enough fibroblasts and collagen, though, so they
eventually can heal. It is better to break a bone than tear a ligament because bones have a
better blood supply and heal faster.
SPRAINS: are tears in a ligament, and are fairly serious. When a tendon or ligament is
sprained, it can take 6 months to heal, and may even need surgery. Even a partial tear, you
have to be careful.
STRAIN: is a tear in a muscle, and is not as bad because it has good circulation and heals
faster. If you can walk on it and it heals in a couple of days, it’s a strain.
BURSAE
• A BURSA is a sack of synovial fluid that is involved in lubrication by serving as a
cushion between a muscle/ligament or tendon/bone, etc. It does not need to be
attached to any bone; it is like a pillow between the muscle and bone.
• Bursae cushion muscles, help tendons slide more easily over the joints, and
sometimes enhance the mechanical effect of a muscle by modifying the direction in
which its tendon pulls.
• It is lined by a synovial membrane which makes its synovial fluid. This fluid can
become excessive during overuse, and pinches nerves in the area. What’s an
inflamed bursa called? Bursitis.
• Crackling sounds in joints are from the release of gas bubbles in the synovial fluid.
• It does not lead to arthritis.
Tendon sheaths are also filled with synovial fluid, and can become inflamed with overuse
(tendonitis).
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TYPES OF SYNOVIAL JOINTS: Characterized by types of movement:
1. PLANE (gliding): like the royal wave of the hand; carpals slide past each other.
2. HINGE JOINTS: one plane; knee, elbow, phalangeal joints
3. PIVOT: Allows only rotational movements, and the rotational movement is in only
one plane: transverse plane. The joint between the first two vertebrae and proximal
radioulnar joint, where the annular ligament on the ulna encircles the head of the
radius. Example is head of radius, C1-C2
4. CONDYLOID: MPJs (metatarsal-phalangeal joints); allow movement in two planes,
so are considered BIAXIAL.
5. SADDLE: base of thumb; biaxial and allows for opposition movement.
6. BALL AND SOCKET JOINTS are MULTIAXIAL. Found in shoulder, hip; lots
of mobility. Some joints have more than one type of motion (wrist).
Important Synovial Joints
Tempomandibular Joint (TMJ)
Knee Joint
Hip Joint
Shoulder Joint
Common Causes of Elbow Pain
• Fractures, ligament sprains and muscle and tendon tears
• Dislocation; usually caused by a fall. Children may dislocate the head of the radius
from being pulled by the arm (nursemaid’s elbow).
• Tennis elbow (lateral epicondylitis) from forceful extension of wrist; wrist extension
is painful. Diagnose by resisting extension of third finger, creating pain in lateral
epicondyle.
• Golfer's elbow (medial epicondylitis) from repeatedly flexing wrists or clenching
fingers
• Olecranon bursitis — inflammation of a small sac of fluid (olecranon bursa) on the tip
of your elbow
Treatment of Elbow and Wrist Pain
• Splinting
• Forearm support bands
• Taping
• Ultrasound
• Oral anti-inflammatory medicines
• Cortisone injections
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The Knee Joint
• The largest and most complex diarthrosis
• of the body
• Hinge joint, but has movements of gliding, rolling and rotation
• 3 articulations: lateral and medial articulations of femur and tibia; intermediate
articulation of patella and femur. Note: Fibula does not articulate with the femur,
only with the tibia.
Extracapsular ligaments of the knee
• Patellar ligament (patellar tendon)
• Medial collateral ligament
• Lateral collateral ligament
The two collateral ligaments prevent the knee from rotating when the joint is
extended.
Intracapsular ligaments of the knee
There are two ligaments that lie inside the joint capsule. They are deep within the joint
cavity, but they are not inside the fluid-filled synovial cavity.
These ligaments cross each other in the form of an X:
 anterior cruciate ligament (ACL)
 posterior cruciate ligament (PCL)
Anterior cruciate ligament (ACL)
• Weaker of the two cruciates
• Slack when knee is flexed, taut when fully extended
• Prevents posterior displacement of femur and hyperextension of knee joint
Posterior cruciate ligament (PCL)
• Taut during flexion, prevents anterior displacement of femur on the tibia
• Is the main stabilizing factor when weight-bearing during flexed knee position (ie.
Walking downhill.)
Menisci of the knee
• Medial and Lateral Menisci
• Crescent (C-) shaped plates of fibrocartilage located over the medial and lateral tibial
condyles
• Thicker laterally, thinner inside the joint capsule
• Act like shock absorbers
• Thicker laterally, taper to thin unattached edges at interior of the joint.
• Menisci absorb the shock of the body weight jostling up and down on the knee and
prevent the femur from rocking from side to side on the tibia.
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Hip Joint
The main factor responsible for stabilizing the hip joint is not the ligament at the fovea
capitis inside the articular capsule. It is also not stabilized by the deep socket. The
ligaments around the head of the femur give it stability.
Abbreviations for finger and toe joints
MPJ: Metacarpal phalangeal joints (fingers) or metatarsal phalangeal joints (toes).
IPJ: Interphalangeal joints (knuckles of fingers and toes)
There are two types of IPJ’s
DIPJ: distal knuckles
PIPJ: proximal knuckles
The thumb (pollex) and big toe (hallux) knuckle is just called its IPJ, but the knuckles of the
other digits are identified specifically as a DIPJ or PIPJ
ARTHRITIS: (“itis” means inflammation). Types:
1. OSTEOARTHRITIS: common in older people. The articular cartilage begins to
break down, and bone spurs start to grow. The surface is no longer smooth, and
movement now causes pain. It is also known as “wear and tear” arthritis. This is the
most common disorder of joints. Can be mild to severe, needing joint replacement.
These people can actually predict the weather, since the synovial fluid is under
pressure. As air pressure changes, fluid expands and hurts more.
2. RHEUMATOID ARTHRITIS: not a disease of old age. It’s an autoimmune
disease where body attacks and destroys the cartilage in synovial joints. They swell
and become unusable, causing knarled hands and feet. Usually need joint
replacements, but that will only last about 15 years. First replacement in 60 years old
is ok, but in a 30 year old, eventually bone degrades and can no longer take the stem
of the implant. It does NOT make many bone spurs; it is degenerative in nature.
3. GOUTY ARTHRITIS (gout). Gout is caused by a genetic error in the metabolism
of uric acid. An gouty episode is triggered by eating too much red meat or protein.
The breakdown product of proteins is urea, which leads to uric acid crystals in the
cooler areas of the body, especially the MPJ’s (metatarsal-phalangeal joints) of the
base of the big toes. The crystals poke the cartilage like needles. Gout is not known
for spur formation, unlike osteoarthritis. Was more common years ago when people
ate nothing but meat. The crystals cause the joint to swell up.
OTHER BONE AND JOINT DISORDERS
Osteomalacia (“malformed bones”) is a genetic malformation of the bones. The
epiphyseal plates are particularly affected.
Rickets is a type of osteomalacia that is NOT genetic; caused by lack of vitamin D. Like
all types of Osteomalacia, rickets also particularly affect the epiphyseal plates.
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Osteomyelitis is an infection of bone.
Achondroplasia is a genetic condition where the bones don’t develop properly and
causes a type of dwarfism. The epiphyseal plates are affected.
Chondromalacia means a problem with the shape of a cartilage joint.
Chondromalacia patella is a condition in which the patella rubs on the femur in the
knee joint. Don’t get this confused with achondroplasia, which is dwarfism!
Paget’s disease is more common in older persons, and may be related to a viral
infection. It is characterized by excessive bone deposition.
Ankylosing spondylitis is a disorder in which vertebrae bind strongly together to limit
the flexibility of the spine.
Synovitis is inflammation of the synovial tissues. May need cortisone injections.
Arthroplasty is a surgical procedure to repair or remodel a damaged joint.
Lyme disease is an inflammatory arthritis of the knee joint, caused from a bacterial
infection after a tic bite.
POLYDACTYLY (MANY DIGITS)
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The extra digit is usually a small piece of soft tissue; occasionally it contains bone without joints;
rarely it may be a complete, functioning digit.
The extra digit is most common on the ulnar (little finger) side of the hand, less common on the
radial (thumb) side, and very rarely within the middle three digits.
These are respectively known as postaxial (little finger), preaxial (thumb), and central (ring,
middle, index fingers) polydactyly.
Polydactyly can occur by itself as an autosomal dominant mutation in a single gene.
But, it usually is one feature of a syndrome of congenital anomalies.
Incidence is 1 in every 500 live births
SYNDACTYLY (FUSED DIGITS)
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In fetal development, syndactyly is normal.
At about 16 weeks of gestation, an enzyme dissolves the tissue between the fingers and toes, and
the webbing disappears.
Syndactyly can be simple or complex.
• In simple syndactyly, adjacent fingers or toes are joined by soft tissue.
• In complex syndactyly, the bones are fused.
Syndactyly can be complete or incomplete.
• In complete syndactyly, the skin is joined all the way to the tip of the finger
• In incomplete syndactyly, the skin is only joined part of the distance to the fingertip.
Fenestrated syndactyly means the skin is joined for most of the digit but in a proximal area there is gap in
the syndactyly with normal skin.
• This type of syndactyly is found in amniotic band syndrome.
• Amniotic band syndrome: Congenital disorder caused by entrapment of fetal parts
(usually a limb or digits) in fibrous amniotic bands while in utero.
Polysyndactyly: extra digits, some of which are fused.
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